This project is designed to understand the rapid increase in autism prevalence in the[unreadable] United States over the past two decades. Proposed are new analyses of complex, multilevel[unreadable] temporally sensitive data sets that will enable me to determine the extent to which[unreadable] familial, environmental, gene-environment, and diagnostic drift/substitution are driving[unreadable] the autism epidemic. Detailed attention to and models capable of capturing social[unreadable] network and social influence underpinnings of the epidemic are developed. New[unreadable] analysis models for intercalating spatial and social network data are developed. These[unreadable] models where appropriate are extended to a wide range of developmental disorders that[unreadable] have increased rapidly in prevalence.[unreadable]